This paper is a review of the past research of mechanical testing methods for natural fibre honeycomb sandwich structure as well as failure modes analysis at a microscopic level by using Scanning Electron Microscope (...This paper is a review of the past research of mechanical testing methods for natural fibre honeycomb sandwich structure as well as failure modes analysis at a microscopic level by using Scanning Electron Microscope (SEM). As the world is garnering attention towards renewable resources for environmental purposes, studies of natural fibre have been increasing as well as the application of natural fibre throughout various industries such as aerospace, automobiles, and construction sectors. This paper is started with brief information regarding the honeycomb sandwich structure, introduction to natural fibre, its applications as well as the factors affecting the performances of the structure. Next, the mechanical testing methods are listed out as well as the expected outcomes obtained from the respective testing. The mechanical properties are also identified by conducting lab tests according to the ASTM standard for sandwich and core structures. The microstructure of the deformed samples is then examined under Scanning Electron Microscope (SEM) by using different magnifications to study the failure mechanisms of the samples. The images obtained from the SEM test are analyzed by using fractography which will show the failure modes of the samples. This article is based on past research conducted by professional on the related topic.展开更多
本文重点在分析比较PMT视频放大系统与PMT光子计数系统的噪声源,信噪比及探测灵敏度的基础上,就光子计数技术在扫描电镜(Scanning Electron Microscope,简称SEM)二次电子信号检测中的可能应用进行了初步的理论探讨。分析表明,SEM采用光...本文重点在分析比较PMT视频放大系统与PMT光子计数系统的噪声源,信噪比及探测灵敏度的基础上,就光子计数技术在扫描电镜(Scanning Electron Microscope,简称SEM)二次电子信号检测中的可能应用进行了初步的理论探讨。分析表明,SEM采用光子计数技术后,信号探测灵敏度可提高一个量级以上,从而在相同的电子枪发射亮度与既定的电子光学系统下,可获得更高的图象分辩率与清晰度。展开更多
Listening Comprehension test of CET-6 has a great adjustment in its item types and weighting of score since December,2015, however, there have been few researches concerning the validity of newly innovated CET-6 liste...Listening Comprehension test of CET-6 has a great adjustment in its item types and weighting of score since December,2015, however, there have been few researches concerning the validity of newly innovated CET-6 listening comprehension test.This paper tries to explore the construct validity and content validity of it. Based on the comparison between the test contents of lis-tening and the test requirements in CET syllabus,it is found that CET-6 listening shows good content relevance. Structural equa-tion modeling(SEM) was used to investigate the construct validity of CET-6 listening, which demonstrates that it mainly tests stu-dents' ability to understand details and inference, while ignoring socio-linguistic competence and psych-physiological compe-tence. Therefore, certain changes are desirable to increase the validity of the listening part of CET-6.展开更多
文摘This paper is a review of the past research of mechanical testing methods for natural fibre honeycomb sandwich structure as well as failure modes analysis at a microscopic level by using Scanning Electron Microscope (SEM). As the world is garnering attention towards renewable resources for environmental purposes, studies of natural fibre have been increasing as well as the application of natural fibre throughout various industries such as aerospace, automobiles, and construction sectors. This paper is started with brief information regarding the honeycomb sandwich structure, introduction to natural fibre, its applications as well as the factors affecting the performances of the structure. Next, the mechanical testing methods are listed out as well as the expected outcomes obtained from the respective testing. The mechanical properties are also identified by conducting lab tests according to the ASTM standard for sandwich and core structures. The microstructure of the deformed samples is then examined under Scanning Electron Microscope (SEM) by using different magnifications to study the failure mechanisms of the samples. The images obtained from the SEM test are analyzed by using fractography which will show the failure modes of the samples. This article is based on past research conducted by professional on the related topic.
文摘本文重点在分析比较PMT视频放大系统与PMT光子计数系统的噪声源,信噪比及探测灵敏度的基础上,就光子计数技术在扫描电镜(Scanning Electron Microscope,简称SEM)二次电子信号检测中的可能应用进行了初步的理论探讨。分析表明,SEM采用光子计数技术后,信号探测灵敏度可提高一个量级以上,从而在相同的电子枪发射亮度与既定的电子光学系统下,可获得更高的图象分辩率与清晰度。
文摘Listening Comprehension test of CET-6 has a great adjustment in its item types and weighting of score since December,2015, however, there have been few researches concerning the validity of newly innovated CET-6 listening comprehension test.This paper tries to explore the construct validity and content validity of it. Based on the comparison between the test contents of lis-tening and the test requirements in CET syllabus,it is found that CET-6 listening shows good content relevance. Structural equa-tion modeling(SEM) was used to investigate the construct validity of CET-6 listening, which demonstrates that it mainly tests stu-dents' ability to understand details and inference, while ignoring socio-linguistic competence and psych-physiological compe-tence. Therefore, certain changes are desirable to increase the validity of the listening part of CET-6.
